I still do think it's a good idea to be realistic about this lens on an NEX-7. It's a totally decent lens on a 14-16mp NEX, as tests have indicated at sites such as photozone. On the NEX-7, however, it can't keep up with the 24mp sensor very well and has been tested as a pretty poor lens; at 18mm the corners never sharpen up to the levels of the Sigma 19mm wide open, even at f/8. At 55mm it must be stopped down to f/8 for decent corner sharpness. A "great" lens would not have these serious limitations.

These are sensor issues more than lens issues. The NEX 7 sensor has known corner issues. Even expensive legacy rangefinder glass that works great on film has issues on this sensor, proving it's not the lens, but the sensor.

The Sigma lens designs probably attempted to rectify this as much as possible, and the fact that they're slow primes would make this relatively easier. The 18-55 is optically very good, but not designed to alleviate this sensor issue. Sony has attempted to fix the issue with the sensor itself (shown in the move from 14MP to 16MP with better micro lenses). The question is when they'll release a large MP sensor with better corner microlenses. Until that happens you're better using SLR lenses or lenses apparently designed around the sensor issue on the 7, such as the Zeiss and Sigma lenses, if you need corner sharpness.

No offense, but in this case it is very clearly not a sensor issue. The Sigma 19mm is sharper on the NEX-7, wide open, than this kit lens is at f/8 at 18mm. The Sony 10-18mm lens is good on the NEX-7 as well. Softness in the corners is an optics problem. This is a cheap kit lens, of course it's not going to have sharp corners throughout its zoom range on a 24mp camera. It would be shocking if it did.

The sensor issues you referred to manifested as color shift in the corners, not sharpness issues as with this kit lens.

I'm only trying to prevent NEX-7 users from being misinformed about the kit lens being a "great" lens on their camera. People turn to this site for information, I'm just trying to help out.